In the past few posts I have been laying out the reasons why I believe that we can be justified in believing in God on the basis of experiences of him that we have; and through testimony, on the experiences of others.
My next basis for believing in God is the very existence of the universe, or anything at all. God, I believe, is the best explanation for why there is something rather than nothing. This is the cosmological argument for God’s existence. A simple way of presenting it is as follows:
- Everything that exists contingently has a cause of its existence.
- The universe exists contingently.
- If the universe has a cause of its existence, then God exists.
- Therefore, God exists.
This is a logically valid deduction, so that if the premises (the first three statements) are true, the conclusion is guaranteed to be true as well. More generally, we can say that the conclusion is at least as likely to be true as the conjunction of the three premises. So if the premises are more plausibly true than false, the conclusion is as well.
So the defense of the cosmological argument comes down to the defense of these three premises. The first premise is a corollary of the principle of sufficient reason. The second premise is intuitive. The third premise is an inference to the best explanation for what the cause of the universe must be like. And from these, the existence of God follows.
For a quick introduction to this version of the cosmological argument, check out this animated video. Contemporary philosophers who defend this cosmological argument include Alexander Pruss and William Lane Craig.
Everything that Exists Contingently Has a Cause
I have defended the principle of sufficient reason (the PSR) at length in previous posts. One way of stating this principle is that every contingent truth has an explanation. Some truths are metaphysically necessary, that is, they could not possibly have been false no matter how reality could possibly have been. Examples of such truths include the laws of logic. It is uncertain how we can explain why such truths are true, aside from the fact that they are necessary.
Other truths are contingent, that is, they could have been false (again in the sense that it is metaphysically possible). These are truths like the fact that dinosaurs are extinct, or that Canada became a country in 1867. As I have written before, it seems to me that such truths all ultimately have a causal explanation, either in the laws of nature or in the choices of personal agents. (I see no other way of explaining truths that are not necessary.) If my earlier defense of the principle of sufficient reason is successful, this immediately implies the first premise: if something exists contingently, there is a cause of its existence.
The reasons that I gave before for the PSR included an argument that the validity of non-deductive forms of reasoning depend crucially on the PSR, an argument for the PSR based on the fact that we never observe any violations of it (things popping into existence without a cause), and an argument for the PSR based on the nature of possibility and necessity. I see these as very powerful reasons to believe the first premise.
Are there reasons to reject the first premise? I have dealt with a number of objections to the PSR in a previous post, and I do not think any of them succeed. Often, though, the atheist who wants to avoid the cosmological argument will just say that the universe is an exception to the first premise: everything that exists in the universe has a cause, but the existence of the universe itself is simply a bare, inexplicable fact.
It is question-begging and arbitrary to make this exception without supporting reasons, so what reasons are there to think that the first premise does not apply to the universe? I cannot see any that do not implicitly presume atheism. (For example, the universe cannot have an explanation, because anything that could explain the universe would just be a state of nothingness. But that assumes that God does not exist, which is circular reasoning as an objection against the cosmological argument.)
In fact, I think there are very good reasons to think that the universe (or anything else, for that matter) cannot be an exception to the principle of sufficient reason. If something can exist with no cause or explanation for its existence, then it effectively is produced out of nothing – and nothing has no properties or attributes that can constrain what kind of things it can produce.
This means that if universes can come out of nothing, anything can. But we simply never observe anything coming out of nothing. Therefore, all of our experience supports the belief that the principle of sufficient reason stands, without exceptions.
(Note: it would be incorrect, I believe, to say that subatomic particles can come out of nothing in phenomena like spontaneous pair production. Rather, according to quantum field theory, particles are excitations in quantum fields that pervade all of space-time. If these quantum fields did not exist, the particles could not be produced.)
(Another note: God himself is not an exception to the first premise, either. The classical theistic position for the last thousand years or so has been that God exists necessarily, rather than contingently. And so the first premise in no way implies that God has a cause: it only talks about contingently existing things.)
The Universe Exists Contingently
It should go without saying that the universe exists. It is a slightly stronger claim to say that it exists contingently: it exists, but it is possible for it to not exist. Nevertheless, I think this second premise is quite intuitive, and more plausible than the alternative assertion that the universe exists necessarily.
It seems extraordinarily ad hoc to say that this universe exists of its own necessity. Physicists (as well as philosophers) often speculate about different quantum fields, space-time structures, initial conditions, or entirely different laws of physics – is it metaphysically impossible that universes with these features could have existed instead of ours? And it seems to me that if such a universe did exist, it would indeed be an entirely different universe – as much as a statue in a different shape and made of a different material is an entirely different statue. If it is possible for a different universe to exist instead of ours, then our universe is contingent.
Going even further, we could ask why a universe like ours exists instead of a fantasy universe like Tolkien’s Middle Earth, or C. S. Lewis’s Narnia. Is there anything metaphysically impossible about those kind of universes? Again, I don’t see anything preventing them, or worlds like them, from being possible worlds (which is part of why they make good stories).
(Note: in contrast, it is not ad hoc to suppose that God exists necessarily, since, unlike the universe, he is a metaphysically simple, perfect being with no arbitrary attributes. Furthermore, other arguments for God’s existence give us independent reasons to believe that his existence is metaphysically necessary.)
One potential response is to say that, while all of these universes are contingent, it is metaphysically necessary that some universe exists. But what on earth could make it necessary for some universe to exist when all of the universes that could exist are themselves not necessary? Moreover, this response does not evade the first premise: a cause is still required for a contingently existing universe.
Another potential response is to say that, in fact, every possible universe really exists necessarily. This avoids being as contrived as saying that only our universe is necessary. But now it violates Occam’s razor in a rather extreme way, and brings a host of philosophical difficulties along with it. (Not the least of which is that it entails a peculiar kind of fatalism, a position that most people take to be absurd.) So it does not seem to me that this is at all a plausible alternative to the second premise, either.
I have one more significant reason to believe that the universe exists contingently, and it is that our universe began to exist. If something has a beginning, it seems entirely possible for it to simply have not begun to exist when it did, and therefore to never have existed at all. So if our universe had a beginning, then its existence is contingent.
In my next post, I will explore the reasons I have to think that the universe began, while taking a detour through a different version of the cosmological argument. Then I will take a look at the justification for the final premise, to complete the argument.